Digital television adapter
A digital television adapter (DTA), or digital-to-analog converter [set-top box], or commonly known as a converter box, is a television tuner that receives a digital television (DTV) transmission, and converts the digital signal into an analog signal that can be received and displayed on an analog television set. It may refer to over-the-air broadcast television signals received by an television antenna, or to cable TV systems which switched to digital cable (a Cable converter box). It normally does not refer to satellite TV, which has always required a set-top box either to operate the big satellite dish, or to be the integrated receiver/decoder (IRD) in the case of direct-broadcast satellites (DBS).
In North America, these ATSC tuner boxes convert from ATSC to NTSC, while in most of Europe and other places such as Australia, they convert from Digital Video Broadcasting (DVB) to PAL. Because the DTV transition did nothing to reduce the number of broadcast television system standards (and in fact further complicated them), and due to varying frequency allocations and bandplans, there are many other combinations specific to other countries.
On June 12, 2009, all full-power analog television transmissions ended in the United States. Viewers who watch broadcast television on older analog TV sets must use a DTA. Since many of the low-power TV stations will continue to broadcast in analog for years to come, consumers who watch low-power stations will need an adapter with an analog passthrough feature that allows the viewer to watch both digital and analog signals. Viewers who receive their television signals through cable or satellite were not affected by this change and did not need a digital television adapter (however, see the cable TV exception below). Additionally, viewers who have newer televisions with built-in digital ATSC tuners will not need an external digital television adapter.
The United States government had set up a program to offer consumers a $40 "coupon" which could be used toward the purchase of a coupon-eligible converter box; that program ended in July 2009.
At the Consumer Electronics Association's Entertainment Technology Policy Summit in March 2006, Federal Communications Commission (FCC) Commissioner Jonathan Adelstein said many Americans did not know about the February 17, 2009, deadline for ending analog TV. Furthermore, he said, too many people were still buying analog TV sets, meaning more demand for converter boxes. And even if people found out what they would have to do, converter boxes might not do the job adequately. Tribune Broadcasting chief technology officer Ira Goldstone said just buying a converter box did not necessarily mean getting the latest technology. Bob Seidel of CBS said companies (especially in countries other than the US) might use cheaper tuners, and people would need new television antennas for proper reception. Circuit City Chairman Alan McCollough opposed converter boxes, saying people should just buy digital TVs, and television networks should offer only widescreen-format television programming as an incentive to do that.
Prototypes of the first converter boxes appeared at the NAB show in 2006. LG Electronics, which took over Zenith Electronics in 1999, showed its model connected to a Zenith TV from 1980, while Thomson Consumer Electronics used an RCA TV from 1987 for its demonstration. Both boxes shown used electronic program guides using Program and System Information Protocol (PSIP). The devices showed program details, V-chip ratings and signal strength. Thomson's model stored three days of TV listings, allowed parental controls, and could set a VCR.
Differences for cable customers
Cable TV systems are under no deadline to convert to digital TV. However, many Comcast (and some other cable TV) customers are finding all of their non-local and non-shopping networks eliminated on various dates, even though only a few are needed for additional digital cable channels. CECBs (Coupon-eligible converter boxes) will not work on these systems because cable ATSC uses 256QAM modulation instead of 8VSB, and so a separate but similar DTA with a QAM tuner is necessary. If the cable company takes away analog channels, at least two of these adapters must be provided for free by the cable company for at least three years (until June 2012), so that customers can continue to watch the same channels with existing equipment.
Most countries that have switched to digital TV use DVB-T broadcasting with MPEG-2 MP@ML encoding. Some, however, consider switching to MPEG-4 H.264 and also tests of DVB-T2 have begun, the UK being the first to test DVB-T2. This results in a number of different combinations for external digital receivers with the MPEG-2 ones sold at about €35 and the MPEG-4 ones reaching €150. Some of these receivers consume the rather high amount of 5W of electricity on standby mode.
- Request for Comment and Notice of Proposed Rules to Implement and Administer a Coupon Program for Digital-to-Analog Converter Boxes, Docket Number 060512129-6129-01 (Jul. 25, 2006).